Path.checkAccess (6873681)

[Rémi Forax]

Usually when a method can fail for different reasons we use different 
exceptions.
checkAccess already returns different kind of IOException so I don't see 
your point.

In my opinion, you should update the doc to says that checkAccess is useless
and also add a link to Attributes.

Rémi

Le 13/10/2010 16:08, Alan Bateman a écrit :
>
> One of methods that needs a bit of re-work is Path's checkAccess 
> method. It's an awkward operation because you either have the 
> requested access or the test fails for any number of reasons. When it 
> fails then you can't reliably determine if it failed because you don't 
> have the requested access, or because you didn't have effective 
> permissions to test the access. A couple of folks have suggested 
> adding the equivalent of File's canXXX methods and there is some merit 
> in that except that a simple boolean doesn't convey the reason when it 
> fails. There is also the security (and performance) argument to simply 
> remove the method as it isn't really needed and you are almost always 
> better to just attempt access to the file and not have a window 
> between the time of the check to the time of the usage. In any case, 
> we need to do something with checkAccess as the exception makes it 
> difficult to use.
>
> One possible approach is to change checkAccess so that it doesn't 
> throw an IOException but instead returns an Access or some object that 
> represents the result of the check, eg:
>
> interface Access {
>  boolean isAllowed();
>  IOException denyReason();
> }
>
> That would allow code such as the following:
>
> if (file.checkAccess(READ,WRITE).isAllowed()) {
> }
>
> -or-
>
> Access acc = file.checkAccess(EXECUTE);
> if (acc.isAllowed()) {
>  :
> } else {
>  IOException ioe = acc.denyReason();
>  :
> }
>
> This approach make it trivial to implement methods such as 
> exception-less isReadable, isWritable, isExecutable if they are needed.
>
> I'm interested to hear if there are folks using checkAccess, whether 
> the IOException has been a problem, and whether a solution along the 
> lines here would be usable.
>
> Thanks,
>
> -Alan.
>
>
> [1] 
> http://download.java.net/jdk7/docs/api/java/nio/file/Path.html#checkAccess(java.nio.file.AccessMode...) 
>
>
>